The invention concerns a method for damping the load impacts in the drive train of a motor vehicle powered by an internal combustion engine and equipped with electronic controls.
The drive train of a vehicle beginning with the engine up to the wheel tread of the drive wheels represents a transmission system which can be excited into more or less damped vibrations in the presence of disturbing factors. In motor vehicles powered by internal combustion engines, a fuel mixture jump occurs in the fuel feed, e.g., in the case of an acceleration process introduced by the driver via the accelerator pedal causing a jump in the load variation represents one such excitation. The load impact resulting due to the jump in the load variation represents a loss of comfort in addition to the excitation of vibration and should therefore be substantially suppressed.
DE 197 53 997 C1 describes a method whereby vibrations can be avoided by influencing the quantity of fuel supplied to the internal combustion engine, thus compensating for the vibrations by adjusting the fuel supply by means of a transmission member. For this purpose, it is proposed that the transmission function of the transmission member be represented as the inverse function to the transmission function of the entire drive train including the fuel metering system (transmission system) and as a fractional rational function in the frequency representation, where the numerator of the fractional rational function is equal to the denominator of the transmission function of the transmission system.
Through the choice of a time constant and a damping magnitude in the numerator of the inverse transmission function, i.e., upon calculation of the present fuel metering, damping of the vibrations is achieved.
Through the choice of an additional time constant and an additional damping magnitude in the denominator of the inverse transmission function, a load impact damping is also accomplished.
The disadvantage is that due to the fixed time constant, the load impact damping is not permanent since, over the service life of a motor vehicle, the vibration behavior of the drive train is subject to relatively great variations.
The objective of the invention is to devise a method for damping the load impacts in the drive train of a motor vehicle driven by an internal combustion engine equipped with an electronic control whereby said cushioning is preserved almost without change over the entire service life of the vehicle, while the number of parameters to be allowed for should remain small in order to simplify the application costs.
According to the invention, this problem is solved by the features of the claim.
With this method one succeeds in avoiding load impacts in the drive train of a motor vehicle in the case of a varying load and in the case of a tip-in, i.e., in the case of a sudden change in the position of the accelerator pedal by the driver. The vehicle can be driven smoothly and free of shaking. The method is characterized by the fact that the load impact damping responds rapidly, that it adapts itself during the entire service life of the vehicle to the varying conditions of the drive train and can be applied at low cost to the electronic control system of an internal combustion engine.